1. Field of the Invention
This invention relates to an ink jet recording apparatus for discharging ink from recording means to a recording medium to thereby effect recording.
2. Related Background Art
A recording apparatus having the function of a printer, a copying apparatus, a facsimile apparatus or the like or a recording apparatus used as the output instrument of a compound type electronic apparatus including a computer or a word processor, or a work station or the like is designed to record images (including characters, symbols, etc.) on a recording medium such as paper, cloth, a plastic sheet or an OHP sheet (hereinafter simply referred to as the recording paper) on the basis of recording information. This recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type, etc. depending on the recording system.
In a recording apparatus of the serial type for effecting recording while main-scanning in a direction intersecting with the conveyance direction (paper feed direction or sub-scanning direction) of a recording medium, the operation of recording (main-scanning) an image by recording means (a recording head) moved along the recording medium, effecting a predetermined amount of paper feeding (pitch conveyance as sub-scanning) after having completed a line of recording, and thereafter effecting the recording (main-scanning) of the image of the next line on the recording medium stopped again is repeated, whereby recording is effected within a desired range of the recording medium. On the other hand, in a recording apparatus of the line type for effecting recording by only sub-scanning in the conveyance direction of a recording medium, the recording medium is set at a predetermined recording position, and a predetermined amount of paper feeding (pitch feeding) is effected while the recording of a line is continuously effected in the lump, whereby an image is recorded within a desired range of the recording medium.
A recording apparatus of the ink jet type (an ink jet recording apparatus) discharges ink from recording means (a recording head) to a recording medium to thereby effect recording, and has the advantages that the recording means is easy to make compact, highly fine images can be recorded at a high speed, recording can be done without any special treatment being required of plain paper, the running cost is low and noise is little because of the non-impact type and moreover, it is easy to use many kinds of inks (e.g. colored inks) to record color images.
The above-described ink jet recording apparatus is generally provided with driving means (in the case of the serial type) for driving a carriage carrying the recording head thereon, conveying means for conveying the recording medium (recording paper), and control means for controlling the driving means and the conveying means. On the other hand, energy generating elements for generating energy utilized to discharge ink from the discharge port of the recording head include one using an electro-thermal converting member such as a piezoelectric element, one for applying an electromagnetic wave such as a laser to thereby generate heat, and discharging ink droplets by this heat generating action, or one for heating liquid by an electro-thermal converting member having a heat generating resistance member.
Among them, recording means (a recording head) of the ink jet type utilizing heat energy to discharge ink as droplets can have its discharge ports arranged highly densely and can therefore effect recording of high resolution. Particularly, a recording head using an electro-thermal conversion element as an energy generating element is easy to make compact and can fully make the most of the merits of IC technology and micro-working technology of which the advance and improvement in the reliability in the recent field of semiconductor are remarkable and is advantageous since it is easy to mount it highly densely and the manufacturing cost thereof is low.
Also, there are various requirements for the material of the recording medium, and in recent years, the development for these requirement is advanced and recording apparatuses using, besides paper (including thin paper and worked paper) which are ordinary recording mediums and resin ordinary sheets (such as OHP), cloth, leather, unwoven fabric and further metals as the recording medium have come to be used.
One of the problems peculiar to the ink jet recording apparatus is the jamming of the discharge ports, and as means for solving this problem, use is generally made of jam recovering means having pump means as intermediary means. Specifically, there is carried out the process of sucking ink from a discharge port (the tip end of a nozzle) by a suction pump to thereby suck and discharge air bubbles in ink of high viscosity in a flow path for supplying ink into a recording head and system or minute dust or air bubbles in ink liquid as waste ink from the discharge port.
To realize jam recovering means, it is necessary to perform the opening and closing operation for a suction cap and the operation of the suction pump. As the means for that, a recovery system designed to change over the forward and reverse rotation of a one-way clutch and a motor and perform two operations arbitrarily is considered to be suitable, but such a recovery system suffers from problems to be solved. One of the problem is that when a transmission mechanism only in one direction (a one-way mechanism) is used for the driving of a cam, drive is not transmitted when a force with which a driven object tries to move faster than a driving speed works, and the driven object moves faster than the drive source (overruns) and the driven object is not stopped although the drive source is stopped on the way. That is, there is the problem that a right result is not obtained.
So, when the one-way transmission method is used, in order not to cause a cam to overrun, it is necessary to make the shape of the cam in a portion in which a cam follower lowers vertical so that the cam follower may not generate a force for causing the cam to overrun, and in that case, it is impossible to effect the control of stopping the cam on the way on which the cam follower is lowered. Also, there is the problem that great shock noise is created when the cam follower falls suddenly.
Also, overrunning can be solved by applying a sliding brake for suppressing rotation to the cam, but in that case, the load of the drive source increases. If an ordinary gear transmission mechanism is used to drive by a drive source having a holding property such as a stepping motor, it never happens that the cam overruns, but since the driving force is always coupled, there is the problem that different control cannot be effected between forward rotation and reverse rotation.
On the other hand, turning an eye to the driving system for the paper supply mechanism, it is seen that there is a further technical task. As an example of the ink jet recording apparatus according to the prior art, description will now be made of an ink jet recording apparatus having ASF (auto sheet feeder) paper supply as first paper supply means and sheet cassette paper supply as second paper supply means.
FIG. 26 of the accompanying drawings typically shows a driving system for the first and second paper feed means and recovery means of an ink jet recording apparatus according to the prior art.
In FIG. 26, the reference numerals 150 and 154 designate gears coupled to a drive source, not shown, and the reference characters 151a and 151b denote pendulum gears, and the gear 151b is rotated counter-clockwisely about the gear 151a when the gear 150 is rotated counter-clockwisely and, is connected to a gear 152a. The paper supply roller of first paper supply means, not shown, is connected to a gear 152b, and the rotation of the drive source is transmitted to the paper supply roller of the first paper supply means.
That is, the drive source connected to the gear 150 is rotated counter-clockwisely, whereby the paper supply roller of the first paper supply means can be rotated.
Next, when the drive source connected to the gear 150 is rotated clockwisely, the gear 151b is rotated clockwisely about the gear 151a and becomes connected to a gear 153a. The paper supply roller of second paper supply means, not shown, is connected to a gear 153b, and the rotation of the drive source is transmitted to the paper supply roller of the second paper supply means.
That is, by the drive source connected to the gear 150 being rotated clockwisely, the paper supply roller of the second paper supply means can be rotated.
On the other hand, when a drive source connected to a gear 154 is rotated clockwisely, a gear 155b is rotated clockwisely about a gear 155a and becomes connected to a gear 156a. By the rotation of a gear 156b, the sucking operation of a recovery system, not shown, is performed.
Next, when the drive source connected to the gear 154 is rotated counter-clockwisely the gear 155b is rotated counter-clockwisely about the gear 155a and becomes connected to a gear 157a. By the rotation of a gear 157b, the operation of the wiper piece of the recovery system, not shown, is performed.
In the above-described example of the prior art, however, it has been necessary to provide two drive sources to perform the recovering operations of two modes and the operation of the two paper supply means, and this has been against the space saving in the apparatus and has led to the problem of increased costs.